you will be sharing accomodation in Australia which would ease the pressure a bit but if you rent say a unit in nth sydney youll be looking at around $500 a week... the further you move away the cheaper it gets.. for example.. move out 35- 40 mins from the city (where i live) and rent is about 250-300 a week for a whole house..

cant tell you what a comfortable wage is over here.. all depends on your spendin habits :P